The invention relates to projectiles or war-heads to fight targets, in particular armoured targets, with an inner arrangement for the dynamic formation of bulging zones and for achieving large lateral effects.
In a plurality of fields of application for projectiles and war-heads it is also desirable, in addition to the demanded penetrating power, to achieve the highest possible effect over area (lateral effect) for increasing the efficiency. This is required in particular in the case of projectiles against flying targets such as fixed wing aircraft, unarmoured helicopters or other aircraft, which from a terminal ballistic viewpoint belong to the easier target classes.
In this field, however, so-called xe2x80x9chardenedxe2x80x9d objects appear increasingly, so that in addition to the high lateral effects partially also high penetrating powers are demanded. The same applies in a comparable way to other structures such as ships, for example. But also in respect of armour-piercing projectiles of high penetrating power, which must be achieved with increasingly slenderer and longer penetrators, securing a sufficient lateral effect during the target penetration or in the target interior is of increasing importance. These requirements apply both to cannon launched kinetic energy projectiles (kinetic energy projectiles) and to war-heads with kinetic energy effective bodies or so-called hybrid projectiles made from kinetic energy effective bodies and hollow charges.
Pursuant to German Pat. No. DE 25 54 600 C1 a solution is prop osed, by means of which an improvement of the lateral effect of kinetic energy projectiles is achieved in such a way that by way of a forward core, which conically tapers in its rear end, the said conical end is delayed on impact and the subsequent penetration process and is pushed in between the prefabricated subprojectiles which are located in the rear, multipart core and accelerates the same radially either immediately or by way of a deformable transition piece. The function of this constructively sophisticated solution was proved both in spin-stabilized and aerodynamically stabilized projectiles (dart projectiles). However, the efficiency is particularly limited owing to the constructional requirements. Particularly where thin target structures are concerned they are not effective. Such solutions are very complex and thus cost intensive. All these factors strongly limit the application.
For the purpose of achieving increased lateral effects tests have been made with projectiles which on impact on a target either fall apart or scatter. These concern effective bodies with brittle steels or hard metals or brittle heavy metals, for example. Such approaches to solutions do not lead to very large splinter conical angles in comparison with the usual penetrators. The possibilities concerning construction and materials are strongly limited in this case too. Moreover, such solutions are preferably suitable for spin-stabilized projectiles only. Moreover, the penetrating power of such projectiles decreases drastically, so that they are only useful for a limited spectrum of applications. Such solutions are particularly less efficient in the case of thinner targets, which also applies to structured targets (multi-plate targets).
In European Pat. No. EP 0 343 389 A1 the projectile core of a discarding sabot projectile is described which consists of a relatively brittle central portion of the projectile core in which a relatively ductile projectile core pin is inserted which is anchored at its rear end in the rear part of the projectile core and at its front end in a tip of the projectile core. For the brittle middle portion of the projectile core frangible tungsten is preferably proposed, whereas the projectile core pin consists of a ductile tungsten, hard metal or any other terminal-ballistically effective material. The relatively brittle middle portion of the projectile core already disintegrates during the penetration of the first target plate of a multi-layer armour-plating, whereas the ductile projectile core pin does not fragment during the penetration process, but instead successively penetrates the following target plates and thus degrades continuously in its length and mass. The relatively thin and thus low-mass projectile element is particularly not suitable for achieving a larger depth effect or for penetrating deeper targets with a continuous lateral effect. The densities of the brittle middle portion of the projectile core and the ductile projectile core pin are nearly the same. A high lateral effect of the splinters in combination with a penetration of multi-layer target plates is thus not given.
WO 92/15836 A1 discloses a spin-stabilized armour-piercing splinter-producing projectile which is formed from a projectile case with a material of high density and a forward head element of the same material in which the disintegration of the projectile case occurs mechanically with the help of a pretensioned heavy material which is located in a pocket hole in the rear part of the projectile casing and a groove in the case structure. Tungsten powder is proposed as compressed filling material. This solution is as ineffective in thin targets as in deep targets. It is also impossible to achieve a terminal-ballistically effective compression in a constructional manner owing to the powdery filling material.
European Pat. No. EP 0 238 818 A1 describes a spin-stabilized discarding sabot projectile which consists of a hollow fragment casing which is closed at the back and front and a projectile tip attached thereto. An inert powder with a density of not less than 10 g/cm3 is proposed. The fragment casing is provided with predetermined breaking points which determine the size of the individual splinters. The fragment casing is to fragment after the penetration of the projectile and break down into individual effective splinters. The powdery filling made from tungsten is ejected after the penetration owing to the rotation of the projectile. A high lateral and, simultaneously, high-depth effect cannot be achieved with such a concept, as the invention is based primarily on the centrifugal forces of a spin projectile and despite prefragmentation the tungsten powder will not sufficiently break down the encompassing thick jacket in the radial direction owing to the natural hollow spaces. Moreover, the powder filling is intended as a replacement for the bursting and burning charge, with the high density being intended to directly produce terminal ballistic effects.
A further fragmentation principle for achieving a lateral effect is proposed in the specification (JP 08061898) in which a reactive metal is arranged in a metal cylinder which reacts chemically thermally with air and water when the armour-piercing ammunition collides with an object. It is obviously intended in this case to produce a xe2x80x9cquasixe2x80x9d explosion and burning effect by the special reaction of the metal so as to achieve a strong radial destructive force.
A non-armour-piercing method to achieve an increased lateral effect with a projectile after the impact on or penetration of a target is known from German Pat. No. DE 28 39 372 A1, in which a projectile is proposed for hunting purposes which consists of a massive projectile casing which is provided with a central pocket hole extending from the front to the rear in which a filling, preferably made from lead, with cavities is introduced. In this design the heavier material is located in the interior of the ambient casing and causes a mushrooming of the forward projectile part during the penetration of the soft target body. In this way the projectile is enabled to transmit its energy to the body of the hunted game in an intended manner and achieve a higher spreading effect. A lateral fragmentation of the projectile body or a lateral splintering effect is not intended, yet it is even undesirable. A similar effect is achieved with the prohibited dum-dum principle against persons.
With respect to solutions provided for armour-piercing projectiles with high penetration power which must be achieved with increasingly slenderer and longer penetrators, few inventions are known whose subject matter is the achievement of a sufficient lateral effect. Usually, the objective of such projectile designs is solely the achievement of a large depth power.
German Pat. No. DE 40 07 196 A1 describes a hyperspeed kinetic energy projectile with a carrying outer casing which encloses a mass body of heavy bulk material, preferably tungsten and depleted uranium powder. In this invention the casing is merely used for the stability of the insert consisting of the heavy metal powder during the launch acceleration and the flying phase. The projectile, which is impacted on the target at a very high speed, achieves its high depth effect because in the hyper speed range the strength of the material of the penetrator no longer or only hardly influences the penetration power. At lower speeds the depth power thus decreases strongly. The lateral effect is marginally low. These projectiles are known as so-called segmented penetrators.
In U.S. Pat. No. 5,440,995 a heavy metal penetrator is presented which is composed of tungsten whiskers. In the case of common penetrators made from polycrystalline tungsten heavy metal, a plastic or hydrodynamic head (mushroom) forms during the penetration of an armoured target, which head influences or reduces the penetrating depth power. The proposed penetrator concept is to prevent this formation of head and thus to increase the depth power. The principle is therefore solely aimed at the achievement of the highest possible depth power. A lateral effect is not given.
A subcaliber kinetic energy projectile with a high length/diameter ratio and a hybrid arrangement is disclosed in European Pat. No. EP 0 111 712 A1 which substantially consists of a main, intermediate and tip body. The intermediate body, consisting of a brittle sintered material of high density such as tungsten or depleted uranium, is connected in a plane abutting joint area on the rear side with the main body and on the front side with the tip body also in a plane abutting joint area, with both the main body and the tip body being formed from a tenacious sintered material of high density such as the aforementioned metallic materials. On impact on an armoured target the particles formed from the brittle material of the intermediate body are to widen the penetration crater and cause a strong blasting effect after the first target plate. Such free buffer layers principally act both in a pressure- and performance-reducing way. The splintering effect remains limited both locally as well as laterally owing to the design and the low differences in density between the brittle and tenacious sintered materials, as the brittle intermediate body is compressed on impact in the axial direction by the tip and main body and, together with these two ballistically highly effective masses, is driven purely axially through the penetration crater.
A further development of the invention as discussed above according to Eurpean Pat. No. EP 0 111 712 A1 is described in German Pat. No. DE 33 39 078 A1 in which the connection between the brittle intermediate body of high density and the ductile main body of also high density, or same density, or even the brittle intermediate body per se is stabilized by a high-strength thin casing. Although this causes an improvement of the stability of the kinetic energy projectile during the launching or flying phase, it does not change however, anything with respect to the terminal ballistic effect as compared with the invention pursuant European Pat. No. EP 0 111 712 A1.
From the state of the art as discussed above one can derive that to date practically no solutions, and particularly no simple ones, are known for an armour-piercing projectile where a high lateral effect is achieved in different targets in conjunction with an adequate depth effect.
It is further known that by using glass bodies which are enclosed under high pressure during impact and penetration of projectiles it is possible to achieve increased lateral effects. These effects are caused by the special dynamic behaviour of glass which has been used for decades in the area of the protection of armour against hollow charges. Accordingly, the use of glass by way of a so-called xe2x80x9ccrater breakdownxe2x80x9d leads to an influence on the stream during the penetration and thus to a considerable reduction of the penetration depth.
Any application of brittle materials such as glass or ceramics as dynamically acting medium is naturally subject to considerable limitations concerning the production techniques for the projectiles and, optionally, warheads and concerning the transmission of forces such as during the acceleration phase of the projectiles and warheads, for example. The technical problems in the introduction of glass into the respective hollow spaces of a projectile body are an example. In prefabricated glass bodies the constructional possibilities for use are strongly limited. Moreover, the arrangement of the contact surfaces with the ambient (enveloping) bodies requires considerable technical efforts. Moreover, glass and ceramics are limited to a certain density range.
In the case of the introduction of glass by way of casting, which means that ceramic materials can principally be omitted owing to the required extremely high sintering temperatures, tensions in the glass body per se would have to be expected by the cooling process even if a perfect casting could be achieved. These tensions may in some cases also have a negative effect on the ambient bodies. Moreover, as was already mentioned above, contact problems would arise on the transition surfaces between the medium and the parts enclosing this medium. But even during the melting of glass temperatures occur which in many cases would lead to impermissible changes in the ambient materials. Moreover, in the use of these fragile and impact-sensitive materials as a dynamically active medium it is not necessary, with the principal exception of pure pressure forces (primarily in the sense of a polydirectional or hydrostatic pressure), to transmit any technical stresses, and thus forces (tension and shearing forces), worth mentioning.
Moreover, in the Germano-French Institute (hereinafter referred to as xe2x80x9cISLxe2x80x9d) experiments with provided glass fibre reinforced plastic materials were performed. It was intended to test primarily whether glass could be replaced as the bearer of the effect and whether in the case of a positive answer to this question it could be assumed, analogously to the protected technology, that the glass content (resin content) or the hardness of the glass fibre reinforced plastic material, for example, are relevant for the operativeness and that consequently with specially highly filled assortments it is possible to achieve a fragmentation factor comparable to pure glass. It is was also proposed to principally verify the previously presumed. xe2x80x9cglass effectxe2x80x9d by changing the resin content.
The experiments confirmed that with glass fibre reinforced materials with a high share of glass (a share of approx. 80% by weight) terminal ballistic effects can be achieved which correspond to those of pure glass as working medium. These first experiments led to the result, however, that with materials which comprise a considerably lower share of glass it is possible to achieve in a surprising manner respective or even considerably higher lateral effects. The thus resulting further considerations and the experiments thus additionally proposed to the ISL and performed there led to the finding that the effects originally described in connection with glass are obviously not so relevant for the increased lateral effects observed in this connection.
According to the latest findings it is important to introduce into a body with terminal ballistic effect or into a casing made from a material which has a terminal ballistic effect a xe2x80x9cbulging mediumxe2x80x9d (hereinafter referred to as AWM) which shows little compressibility and comprises a comparably low density or terminal ballistic power in comparison with the actual effective bodies. The same naturally also applies in the case that the AWM is located between an outer body with terminal ballistic efficiency and a central penetrator.
The terminal ballistic power of an effective body is determined in the range of lower impact speeds (below 1000 m/s) by its mechanical properties and its density, and in the upper speed range (more than 1000 m/s) increasingly by its density.
In the doctoral thesis xe2x80x9cDas Verhalten von Kupferstiften beim Auftreffen auf verschiedene Werkstoffe mit Geschwindigkeiten zwischen 50 m/s und 1650 m/s (The behaviour of copper pins on impact on various materials at speeds between 50 m/s and 1650 m/s)xe2x80x9d by Dipl.-Ing. Gxc3xcnter Weihrauch of Feb. 12, 1971 of the University (TH) Karlsruhe and in the ISL report with the same, name a number of things are said about this behaviour on pages 98 to 101. The following pressure balance arises in a co-ordinate system which is moved along with the stagnation point:
xc2xdxcfx81P*(vxe2x88x92u)2=xc2xdxcfx81Z*u2+F
with v=projectile speed, u=penetration speed, xcfx81P=density of the projectile material, xcfx81Z=density of target material, F=factor which is changeable with the bulging speed of the bulging zone and depends both on the dynamic tenacity of the target and of the projectile material and thus also of the AWM.
Accordingly, the influences arising from the compressibility of the material and the dissemination speeds of the elastic and plastic faults are also included by way of term F. At higher speeds v of the projectile the share of F decreases and the known Bernoulli""s equation applies with sufficient accuracy:
xc2xdxcfx81P*(vxe2x88x92u)2=xc2xdxcfx81Z*u2
From this equation one receives for the penetration speed u, which also known as crater base speed, a term where the speed u only depends on the projectile speed v and the material densities xcfx81Z and xcfx81P:
u=v/(1+(xcfx81Z/xcfx81P)).
If the projectile does not consist of a uniform material, this term applies under the prerequisite of high projectile speed v for every single material in the projectile, with the respective material density such as xcfx81AWM or xcfx81Casing having to be inserted for xcfx81P.
It can easily be derived therefrom that materials with lower density than the actual penetrator material with high terminal ballistic power will achieve lower penetration speeds at high projectile speeds and thus will remain behind in the target as compared with the ballistically highly effective penetration material.
At relatively low projectile speeds F becomes a speed term on an equal standing, i.e. the dynamic strengths of the materials involved are co-decisive. For the achievement of rapidly commencing and high lateral effects, materials with low strength should be used as bulging medium. Concerning the density one still has a relatively large amount of leeway.
Accordingly, at high projectile speeds (more than 1000 m/s) one can vary the density of the AWM, because then the mechanical properties do not play any major role any more.
At very high speeds (1500 m/s up to several km/s) one can usually entirely neglect the dimensional stability of projectile and target material, so that the strength of the materials involved does not play any role any more. In this case metallic and other materials can be treated approximately as liquids.
The speed from which the strength of the matter can be ignored depends, however, strongly on the respective properties of the material. Accordingly, these impact phenomena from the high-speed range already occur at relatively low speeds when dense and simultaneously dynamically soft materials such as lead, copper or tantalum are involved.
These considerations show that the effectiveness of the arrangements as proposed here is not limited to a specific speed range, but is present both from relatively low impact speeds (some 100 m/s), as occur at large fighting distances for example, right up to very high impact speeds in the magnitude of several km/s, as occur for example in impact situations with so-called tactical missiles (TBM defence).
In line with the above considerations it is necessary to influence the dynamics of the inner bulging zone in projectiles and war-heads over wide limits and with very simple means.
It is therefore an object of the present invention to arrange projectiles and war-heads with simple means in such a way that the same can both achieve a strong lateral effect and simultaneously ensure high penetration depths if required.
This object, and others which will become apparent hereinafter, is attained in accordance with the present invention by radially encompassing a bulging medium in the form of a material which is substantially terminal-ballistically ineffective by an outer body in the form of a penetration material which is considerably more terminal-ballistically effective.
Further features, details and advantages arise from the description below in conjunction with the claims and the individual figures.